#include <bits/stdc++.h>
using namespace std;
using uint=unsigned int;
using ll=long long;
using ull=unsigned long long;
using i128=__int128;
const int N=1e6+5;

void solve(){
    ll n;
    cin>>n;
    ll h=1;
    while(h<=n){
        h<<=1;
    }
    if(h-1>n)cout<<h-1;
    else cout<<n;
    return;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    solve();
    

    return 0;
}